XenForo moderator

You could use the container_public_params event to add it to the container params. That would allow you to access the variable in PAGE_CONTAINER and other included templates. But if you need it in your content template then you need to add it to the controller, in a _postDispatch function perhaps (to affect all actions). Or maybe the front_controller_pre_view event will work as it has access to the controllerResponse.